Screw.



SCREW.

APPLICATION FILED MAY 27, 1913.

Patented Mar. 3, 1914.

E. J. POREMAN.

Inventor,

i S y e n r o t t A uff/wm@ rr I 114A, W Il 1411911!! Witnesses Y wood screw with the threa of provided with la longitudinal groovev toq f- ERNEST Jarromiiir, 'or TRINIDAD, coLonADo.

scnfnw..

Specification ot Letters Patent. applicati@ mai may saisis. semi No. 770,238',

Patented Mar.- 3,19i4'.

To all lwhomjit may concern -Be it known that I, ERNEST J. FOREMAN, a citizen of the United States, residing at Trinidad, in the county of Las Animas and State of Colorado, have invented a new-l and useful Screw, of which the following is a specification.

This invention relates toimprovements in:` f

llar reference numerals designate correspondwood screws and more gticularly ItloY a portion t ereprevent the accidental displacement of the screw.

A further object is ,to provide a wood screw with a mutilated portion which offers no. increased resistance to :the .insertion ofl the screwwitliin a. substance but successfully prevents the retraction'thereof unless a larg'eforce is applied.

dinal groove along the threaded portion of 4'a wood screw' with one face thereof4 cut sha; 1y and in a radial manner and to round ofr't e opposite, facefof the groove. T he sharp or radial face is so positioned that it will be leading portion or face of the a followin position and which will contactl rous material so as to hol'drthe-V with the said screw ,against retraction.

, thatchanges inthe'precise embodiment of the invention herein disclosed, `can be made within the scope of whatis claimed, without departing from the spirit of the invention.

In the drawings accompanying i'tnis speci fication and forming a' part' thereof, the

` the bers' crowdfinto the cut A further object is to provide .Valongitu-l of the following face 1 apparent, change the lea With-.the foregoing and other objects in` view which will appear as `the description` proceeds, the invention resides in the' com-` ination and arrangement of parts and in 4the details of construction hereinafter described and claimed, it'being understood retraction thereof."A Fig. 2 is a fragmental view in elevation of a woodfscrew constructed along the lines of my invention. 3

ine

is a cross sectional view taken on the A A of Fig. 2 lookin in an upward direction,` and with the ead or upper'portion of the screw omitted.

y Referring to the drawings in which simiing parts throughout the several views,`1 is the shank of a wood screw rovided with the threaded portion 2, the t reads consisting of the' `raised helical-Bauges 3 of the ordina cbntour. The upper extremi the s ank is provided with the usua enlarged" head `4: for the engagement of the screw and affords means for the rotating thereof In order that the wood screw as herein disclosed may be inserted or driven into wood or similar material with approximatelyl the same force as necessary in the inserting of a wood screw of the ordinary type, and to further 4providev that the .screw having once assumed its inserted position, any tendency to retract the same will` encounter a greatly increased resistance to thus prevent the accidental displacement of the screw, a groove or channel 5 is cut along- 35 the threaded ortion of the screw 'and the cross sectiona contour of the said channel asillustrated in Fig. 2 lends particular properties tothe screw. y ,i

The leading face 6 of the channel when the screw is being driven inwardly extends sharp ab- Irupt faces for the mutilated threads'. lThe substantially radial and provides following face 7 of the channel taken with respect to the inserting of the screw is formed along a gradual slope and may be likened to a spiral curve of constantly increasing radii, the Aresult of so cutting lthis face bein in width dus to the triangular `cross sectional contour of a thread so that the wood fibers which come in contact with the spiral face e of the groove are compressed by the same in a gradually increasing manner so that the fibers of the substance in which the screw is inserted, usually wood, are compressed by the threads and crowded into a limited space and due to the sloping face the Vgroove will not cut or mutilate the libersduring the inserting v of the screw. into the wood.` When, however, a forcefis exerted upon the that the face gradually decreases screw tending to retract the same, the'fibers f left by the receding face of the groove, and i thus. the sharp abrupt following face of. the

- groove will come into contact lwith the said fibers fand thus a rotation to retract: thescreW will tend to dislodge and tear the fibrous structure of' the wood'which will therefore olier considerable resistance tothe Q u l grooves for tlre-f` eutz'material to deposit 1n so that the device cuts; its; way clean.1 Also;

same. The abrupt face therefore will se; curely lock the screw in its embedded position and prevent the accidental retraction thereof. i t

Attention is called to the fact that in the i usual screw the same after being embedded within a iibrous structure forces the said i fibers apart and for a certain length of time the fibers will resiliently engage and hold the screw in position. Howeven after a y,

period of time has elapsed the fibrous structure becomes set and will no lon'ger resiliently engage the surface of the screw and when a slight shrinkage of the wood now takes place the set position of the fibers draw away from the surface of the screw which will allow it to become accidentally displaced. With the screw as disclosed in y the prcsentapplication the abrupt leading face during the inserting of the screw has no eiiect upon the forming of the aperture or the vdisplacing of the wooden fibers.

structure and crowds the same to one side of theI threads. When the screw Ihas assumed its final position, the fibrous structure crowd into the opening between the faces of the groove and become set in this position. Should the wood now shrink it The following spiral face compresses the fibrous noasbsea will' not loosen the screw and does not: shrink enough to draw entirely froment vofA the f -faces of the groove. The retraction ,of the screw? is*` therefore et'ectaial-lyf pret-- vented! unless considerable foncez isy exerted by the abrupt: face com-ing into'contactwithf theiibrous structure: and wedging; the; same?,

in front; of the said abruptl facer The devices as: herein disclosed is; to; ha4

distinguished from and. noty to; heb, confused with those devicesy which are provided. with.

mentionv isA made. of. the; fact that the.l nurnber,y and exact sha-pe ofv the longitudinal axis, ofv the groove. may` be varied as'. will.

v shank said threaded shank providedv with:

a groove. extending longitudinally" thereof; the front or leading face of the groove con.- si'dered during' the insertion of the screw t extending substantially radial of the.. said i threaded shank, the opposite `face of. said groove of sloping outline, the said sloping face adapted to compress material in contact, therewith during' the insertlon ofthe screw,

the radially extending face of the; groove adapted to Contact with the compressed fibrous material to greatly increase the effective resista-nce to the movements of the screw 'during the retract-ion thereof'.

In testimony that I claim the foregoing as my own, I have hereto aiixed'my Signature in the presence ot two witnesses.

ERNEST JAY FOREMAN. Witnesses:

THos. A.- CoRBoULD, FRANK'R. DUNLAvy. 

